Plasma processing apparatus and method

ABSTRACT

Disclosed is a plasma processing apparatus and a plasma processing method, by which ions of plasma can be injected uniformly over the whole surface of a substrate to be processed, in a short time. Specifically, when the substrate is processed in a reaction container, the gas pressure inside the reaction container is increased. Alternatively, the distance between a plasma processing portion and the substrate is enlarged, or the substrate is temporally moved outwardly of the reaction container. As a further alternative, a shutter is disposed between the plasma producing zone and the substrate. With this procedure, incidence of ions of the plasma upon the substrate can be substantially intercepted for a predetermined time period from the start of plasma production.

FIELD OF THE INVENTION AND RELATED ART

This invention relates to plasma processing apparatus and method forinjecting ions of plasma into a whole surface to be processed, uniformlyand in a short time. Such apparatus and method will be particularlysuitably usable in production of microdevices having an extraordinarilyfine pattern, such as semiconductor chip (e.g. VLSI: very large scaledintegrated circuit), LCD (liquid crystal display), CCD (charge coupleddevice), thin-film magnetic head, micromachine, etc.

In recent attempts to meet further increases in density of semiconductordevices, silicon oxynitride films are used as a gate insulating film ofa thickness not greater than 3 nm. The silicon oxynitride film isproduced by introducing nitrogen into a silicon oxide film. The siliconoxynitride film has high relative dielectric constant, and also it has afunction for reducing leakage current or boron diffusion from a gateelectrode. Because of these superior characteristics, the siliconoxynitride film is becoming an attractive material.

As regards the method of nitriding a silicon oxide film, a thermalprocess, a remote plasma process, and a microwave plasma process, forexample, have been proposed.

The first method, i.e., a silicon oxynitride film forming method basedon thermal processing, is that a wafer is heated for a few hours in anitric monoxide gas ambience. This method is to thermally nitride thesilicon oxide film.

In this method, however, the wafer is heated to a high temperaturearound 800 to 1000° C. and, thus, nitrogen easily moves inside thesilicon oxide film and reaches the interface between the silicon oxidefilm and the silicon. Since there is a difference in respect to easinessof diffusion between the silicon oxide film and the silicon, nitrogen isaccumulated at the interface between them. Hence, as regards a nitrogenconcentration distribution in depth direction inside the silicon oxidefilm resulting from the thermal nitriding process, nitrogen is notlocalized at the surface while, on the other hand, the nitrogenconcentration at the interface between the silicon and the silicon oxidefilm becomes high. Since the nitrogen concentration at the interfacebetween silicon and silicon oxide film is high, the devicecharacteristic will not be good. Further, because of high temperaturetreatment of a wafer at around 800 to 1000° C., substances other thannitrogen will be diffused together, and this will make the devicecharacteristic worse. Furthermore, there is another problem that theprocess time is quite long.

The second method, i.e., a silicon oxynitride film forming method basedon remote plasma processing, is that nitrogen ions in nitrogen plasmaare sufficiently reduced and only nitrogen active species are conveyedto a wafer, to nitride a silicon oxide film. According to this method,while using nitrogen active species having high reactivity, a siliconoxide film can be nitrided at a relatively low temperature around 400°C. By keeping a reaction container at a high pressure or by separating aplasma producing zone and a wafer far away from each other, nitrogenions inside the plasma are reduced so that only nitrogen active speciescan be used. Regarding the nitrogen concentration distribution in depthdirection inside the silicon oxide film resulting from the remote plasmaprocessing, it can be made larger at the surface and it can be madesmaller at the interface between silicon and silicon oxide film.

According to the remote plasma processing method, however, sincenecessary nitrogen active species will be reduced together with nitrogenions inside the plasma, it is not easy to obtain sufficient nitrogenactive species and thus the processing time is very long. Furthermore,there is another problem that, since the nitrogen concentrationdistribution in depth direction inside the silicon oxide film decreasessharply with the depth, it is difficult to assure an increased nitrogensurface concentration.

The third method, i.e., a silicon oxynitride film forming method basedon microwave plasma, is that nitrogen ions are injected into a siliconoxide film at a low injection energy not greater than 5 eV, thereby tonitride the silicon oxide film.

According to the silicon oxynitride film forming method using microwaveplasma, as compared with the two methods described above, the microwaveplasma is at a low electron temperature around a few eV and, therefore,the ion injection energy can be made not greater than 5 eV. As a result,nitrogen can be localized approximately in a 2-nm top surface layer ofthe silicon oxide film, while assuring a state that substantially nonitrogen is present at the interface between the silicon and the siliconoxide-film. Furthermore, since the wafer is processed by high densityplasma mainly composed of ions, the processing time can be shortenedadvantageously.

According to this plasma processing method, however, there is apossibility that, within a very little time till the localized plasmaspreads over the whole surface of a dielectric material window, ions inthat plasma locally nitrides the silicon oxide film to thereby degradethe nitrogen uniformness of the silicon oxide film. Furthermore, sincethe silicon oxide film is processed by high density plasma, the timerequired for producing a silicon oxynitride film of desired nitrogenconcentration is short so that the little time described above can notbe disregarded.

SUMMARY OF THE INVENTION

It is accordingly an object of the present invention to provide a noveland improved plasma processing apparatus by which at least one of theinconveniences described above can be removed or reduced.

It is another object of the present invention to provide a novel andimproved plasma processing method by which at least one of theinconveniences described above can be removed or reduced.

In accordance with an aspect of the present invention, there is provideda method of processing a substrate to be processed, in a reactioncontainer by plasma, the improvements comprising substantiallyintercepting incidence of ions of the plasma upon the substrate, for apredetermined time period from start of production of the plasma.

Here, the term “predetermined time period” refers to the time afterstart of plasma production and till the plasma distribution isstabilized to a level that nitriding uniformness of a substrate to beprocessed is not degraded. This time can be determined by actualmeasurement and, for example, it is about 1-5 seconds. Also, the term“substantially intercepting” refers to that ion flux is reduced to about1/10 or less of that during an actual processing operation.

The intercepting means may be one of pressure controlling means forincreasing the gas pressure inside the reaction container forsubstantial ion interception, shutter means disposed between the plasmaproducing zone and the substrate to be processed, stage means forretracting the substrate to a position not to be irradiated with ions,and stage means for moving the substrate away from the plasma producingzone.

The pressure controlling means may increase the gas pressure inside thereaction container, for ion interception, to not less than five timeshigher than that during an actual processing operation and yet to notlower than 100 Pa.

The plasma may preferably be microwave plasma. Particularly, microwavesurface-wave plasma having producing-zone plasma density ofapproximately 10¹¹/cm³ or more will be effective. Since the microwavesurface-wave plasma has a high density, if the amount of ions to beinjected into the substrate to be processed should be reduced, theprocessing will be completed in a few seconds. However, with suchshort-time processing, local processing of the substrate by locallyproduced plasma can not be disregarded. Hence, in the case ofhigh-density plasma such as microwave surface-wave plasma, in regard tothe uniformness it is important to prevent only ions of the plasma, atits early stage of production, from being incident on the substrate tobe processed.

In accordance with the present invention, during a period from start ofplasma production to plasma stabilization, ions of the plasma aresubstantially prevented from being incident on the substrate to beprocessed. As a result, the whole surface of the substrate can beprocessed with uniform ion density. Thus, high-density plasma can beused, and ions of the plasma can be injected over the whole surface ofthe substrate uniformly and in a short time.

These and other objects, features and advantages of the presentinvention will become more apparent upon a consideration of thefollowing description of the preferred embodiments of the presentinvention taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic and sectional view of a microwave surface-waveplasma processing apparatus according to a first embodiment of thepresent invention.

FIG. 2 is a graph for explaining the relation between ion density anddistance from a dielectric material window.

FIG. 3 is a schematic and sectional view of a microwave surface-waveplasma processing apparatus according to a second embodiment of thepresent invention.

FIG. 4 is a sectional view taken along a line A-A′ in FIG. 3.

FIG. 5 is a schematic and sectional view of a microwave surface-waveplasma processing apparatus according to a third embodiment of thepresent invention.

FIG. 6 is a schematic and sectional view of a microwave surface-waveplasma processing apparatus according to a fourth embodiment of thepresent invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will now be describedwith reference to the attached drawings.

In accordance with the present invention, when a surface of a substrateto be processed is processed by plasma, only ions of the plasma at anearly stage of production are substantially prevented from beingincident on the substrate. By reducing ion flux, reaching to thesubstrate during plasma production, approximately to 1/10 or less ofthat during an actual processing operation, it is assured that thesubstrate is processed uniformly.

First Embodiment

In accordance with a first embodiment of the present invention, the gaspressure in a reaction container is made not less than 10 times higherthan that in an actual processing operation and yet not less than 100Pa. Subsequently, plasma is produced, and only ions in the plasmalocally produced are prevented from being incident on a substrate to beprocessed. After plasma discharging becomes stable, the gas pressure islowered to allow an ion flux to impinge on the substrate, whereby plasmaprocessing of the substrate is carried out.

FIG. 1 illustrates a general structure of a microwave surface-waveplasma processing apparatus according to the first embodiment of thepresent invention. In FIG. 1, the apparatus comprises a plasmaprocessing chamber 1, a substrate carrying table 3 for holding asubstrate 2 thereon, a heater 4, a processing gas introducing means 5,an exhaust port 6, a slotted endless circular waveguide tube 8, slots 11formed in the waveguide tube 8 at an interval corresponding to ½ or ¼ ofthe wavelength inside the microwave tube, a dielectric material window 7for introducing microwaves into the plasma processing chamber 1, and acooling water flowpassage 10 formed in the waveguide tube 8. The innerwall of the plasma processing chamber 1 and the dielectric material 7are made of quartz, having no possibility of causing metal contaminationof the substrate 2. The substrate table 3 is made of ceramics thatcontains aluminum nitride as a main component, while taking into accountthe metal contamination and thermal conduction of the heater 4. Denotedat 24 is a pressure detector for detecting the pressure inside theplasma processing chamber 1, and denoted at 25 is a pressure adjustingvalve for adjusting the pressure inside the plasma processing chamber 1on the basis of the opening of the valve. Denoted at 26 is a vacuum pumpfor evacuating the plasma processing chamber 1. The pressure detector 24may be a commercially available detector such as Baratron Pressure Gaugeavailable from MKS Instruments AG, and the pressure adjusting valve 25may be a commercially available one such as Dry Pump available fromKatayama Seisakusho Co.

In an early stage of plasma production and until locally produced plasmaspreads over the whole surface of the dielectric material window 7, ifthe pressure inside the plasma processing chamber 1 is raisedapproximately over 130 Pa, ions in the locally produced plasma do notreach the substrate 2. Thus, local processing of the substrate 2 can beavoided.

On the other hand, after plasma discharging becomes stable, if thepressure inside the plasma processing chamber 1 is lowered toapproximately below 130 Pa, ions in the plasma can reach the substrate2, whereby the substrate 2 can be processed uniformly.

Hence, the inside gas pressure of the reaction container is raisedapproximately over 130 Pa and, after that, plasma is produced.Subsequently, the gas pressure is lowered to approximately below 130 Pa.With this procedure, local ion injection to the substrate can be avoidedand, thus, uniform ion density can be provided over the whole surface ofthe substrate to be processed.

In the microwave plasma processing, plasma is produced adjacent adielectric material window that functions as a microwave introducingport. By diffusion from there, plasma is conveyed to a substrate to beprocessed and the substrate is processed thereby.

FIG. 2 illustrates an example of the relation between ion density anddistance from a dielectric material window. It is seen in the drawingthat, at a gas pressure approximately larger than 130 Pa, ions in theplasma are reduced rapidly with an increase of the distance from theplasma producing zone, due to recombination quenching with electrons ora decrease of diffusion length. At a distance of about 10 cm from theplasma producing zone near the dielectric material window, ions arereduced to about 1/100. Hence, by producing plasma after the gaspressure is raised to about 130 Pa, local processing of the substrate bylocally produced plasma can be reduced and, even if the substrate isprocessed in a little time, sufficient uniformness is obtainable. Also,by subsequently decreasing the gas pressure to a desired pressure lowerthan approximately below 130 Pa, ions of the plasma can be conveyed tothe substrate, to be processed, efficiently without a large loss suchthat the substrate can be processed in a short time. Particularly, ifthe gas pressure is made lower than about 130 Pa, at a distance of about10 cm from the plasma producing zone, ions in the plasma are reduced byonly a fraction of those at the plasma producing zone and, therefore,the substrate can be processed quickly.

An example of plasma processing that uses the plasma processingapparatus of the first embodiment will be described later as a FirstExample.

Second Embodiment

In accordance with a second embodiment of the present invention, aspecific member is disposed between a plasma producing zone and asubstrate to be processed, so as to substantially prevent plasma ionsfrom being incident on the substrate. Subsequently, plasma is producedand, after the plasma discharging is stabilized, the above-describedmember is placed so that ions of the plasma can be projected on thesubstrate. With this arrangement, only ions of plasma locally producedat an early stage of plasma production are prevented from being incidenton the substrate to be processed.

FIG. 3 illustrates a general structure of a microwave surface-waveplasma processing apparatus according to the second embodiment of thepresent invention. FIG. 4 is a sectional view taken along a line A-A′ inFIG. 3, for explaining a movable quartz window mechanism of FIG. 3. InFIGS. 3 and 4, the plasma processing apparatus comprises a fixed quartzplate 31 having plural holes formed therein, a reciprocally movablequartz plate 32 having plural holes formed therein, a quartz cylindricaltube 30 for portioning between an operational portion of the movablequartz plate 32 and a substrate to be processed, holes 33 provided inthe movable quartz plate 32, holes 34 provided in the fixed quartz plate31, a bellows 35, and a linear motion device 36 such as a linearactuator, for example, for reciprocally moving the movable quartz plate32. The linear motion device 36 is disposed at the atmosphere side. Thecomponents of this embodiment corresponding to those of the firstembodiment are denoted by like numerals, and description therefor willbe omitted.

The movable quartz plate 32 takes a position B where the holes of themovable quartz plate 32 and the holes of the fixed quartz plate 31 areregistered and the conductance becomes largest, and a position C wherethe holes of the movable quartz plate 32 and the holes of the fixedquartz plate 31 are mutually deviated and the conductance becomessmallest. By means of the linear motion device 36, the movable quartzplate 32 is reciprocally moved between these positions.

In the second embodiment, the procedure is as follows. First of all, bymeans of the linear motion device 36, the movable quartz plate 32 isplaced at the position C. Subsequently, plasma is produced like thefirst embodiment. After the plasma is spread over the whole surface ofthe dielectric material window 7, the movable quartz plate 32 is movedto the position B.

By keeping the movable quartz plate 32 at the position C until locallyproduced plasma is spread over the whole surface of the dielectricmaterial window 7, ions of the locally produced plasma are preventedfrom reaching the substrate 2 to be processed. Therefore, localprocessing of the substrate 2 can be avoided.

When the movable quartz plate 32 is placed at the position B, ions inthe plasma can be diffused over the substrate 2, and thus the substrate2 can be processed uniformly.

Hence, in accordance with this embodiment, a specific member is disposedbetween the plasma producing zone and the substrate to be processed soas to substantially prevent ions of the plasma from being incident onthe substrate, and after that plasma is produced. After the plasmadischarging is stabilized, the specific member is disposed to allow ionsof the plasma to enter the substrate to be processed. With thisarrangement, only ions of locally produced plasma are prevented frombeing incident on the substrate, and thus uniform ion density can beprovided over the entire surface of the substrate.

Third Embodiment

In accordance with a third embodiment of the present invention, plasmais produced inside a reaction container and, after the plasmadischarging becomes stable, a substrate to be processed is conveyed intothe reaction chamber. With this arrangement, only ions of locallyproduced plasma can be prevented from being incident on the substrate tobe processed.

FIG. 5 illustrates a general structure of a microwave surface-waveplasma processing apparatus according to the third embodiment.

In the drawing, the plasma processing apparatus includes a pre-chamber40, a bellows 35, and a linear motion device 36 for reciprocally movinga substrate carrying table 3. The linear motion device 36 is provided atthe atmosphere side. The components corresponding to those of the firstembodiment are denoted by like numerals, and description therefor willbe omitted.

The substrate carrying table 3 is made reciprocally movable between aposition D where the substrate 2 can be exposed to ions of plasma, and aposition E inside the pre-chamber 40 where the substrate 2 is not easilyexposed to the plasma ions. At the position E, the clearance between thepre-chamber and the top surface of the substrate carrying table 3 is afew millimeters to 1 cm, and this arrangement makes it difficult forplasma ions to impinge on the substrate 2 to be processed.

In the third embodiment, the procedure is as follows. First of all, bymeans of the linear motion device 36, the substrate carrying table 3 isplaced at the position E. Subsequently, plasma is produced like thefirst embodiment. After the plasma is spread over the whole surface ofthe dielectric material window 7, the substrate carrying table 3 ismoved to the position D.

By keeping the substrate carrying table 3 at the position E untillocally produced plasma is spread over the whole surface of thedielectric material window 7, ions of the locally produced plasma areprevented from reaching the substrate 2 to be processed. Therefore,local processing of the substrate 2 can be avoided.

When the substrate carrying table 3 is placed at the position D, ions inthe plasma can be diffused over the substrate 2, and thus the substrate2 can be processed uniformly.

Hence, in accordance with this embodiment, after plasma is producedinside a reaction chamber, a substrate to be processed is conveyed intothe reaction chamber. With this arrangement, only ions of locallyproduced plasma are prevented from being incident on the substrate, andthus uniform ion density can be provided over the entire surface of thesubstrate.

Fourth Embodiment

In accordance with a fourth embodiment of the present invention, first asubstrate to be processed and a plasma producing zone are spaced apartfrom each other and then plasma is produced. After the plasmadischarging is stabilized, the substrate and the plasma producing zoneare placed closer to each other. With this procedure, only ions oflocally produced plasma are prevented from being incident on thesubstrate to be processed.

For example, with a gas pressure of 13 Pa and at a position spaced byabout 20 cm from the plasma producing zone, ions of the plasma will bereduced to about 1/100, according to extrapolation based on the graph ofFIG. 2. Hence, the substrate 2 is first separated from the plasmaproducing zone by about 20 cm and then plasma is produced. With thisprocedure, local processing by locally produced plasma can be reducedsuch that the substrate can be processed uniformly. Also, bysubsequently moving the substrate toward the plasma producing zone to adistance under about 20 cm, ions of the plasma can be conveyed to thesubstrate efficiently without a large loss. Thus, the substrate can beprocessed in a short time. Particularly, if the substrate to beprocessed is placed at a distance of about 10 cm from the plasmaproducing zone, ions in the plasma will be reduced by only a fraction ofthose at the plasma producing zone and, therefore, the substrate can beprocessed quickly. If the gas pressure is raised, a similar effect isobtainable even when the distance between the plasma producing zone andthe substrate is made shorter.

FIG. 6 illustrates a general structure of a microwave surface-waveplasma processing apparatus according to the fourth embodiment of thepresent invention.

In the drawing, the plasma processing apparatus includes a bellows 35and a linear motion device 36 for moving a substrate carrying tableupwardly and downwardly. The linear motion device 36 is disposed at theatmosphere side. The components of this embodiment corresponding tothose of the first embodiment are denoted by like numerals, anddescription therefor will be omitted.

The substrate carrying table 3 takes a position F which is approximately10 cm from a dielectric material window 7 and a position G which isapproximately 20 cm from the window 7, and by means of the linear motiondevice 36, the substrate carrying table 3 is made movable upwardly anddownwardly between these positions. The processing pressure at that timemay be 13 Pa.

At a gas pressure 13 Pa and at position G which is about 20 cm from theplasma producing zone, ions of the plasma will be reduced to about 1/100or less, according to extrapolation based on the graph of FIG. 2.Furthermore, at the position F which is about 10 cm from the plasmaproducing zone, ions of the plasma will be reduced by only a fraction ofthat at the plasma producing zone. This means that the processing amountat the position G will be an order of one-tenth, one-twentieth, etc. ofthat at position F.

By holding the substrate carrying table 3 at the position G untillocally produced plasma is spread over the whole surface of thedielectric material window 7, the processing amount of the substrate 2by the ions of locally produced plasma can be suppressed to a level ofan order of one-tenth, one-twentieth, one-thirtieth, etc. of that at theposition F.

Hence, in accordance with this embodiment, the substrate carrying table3 is first placed at the position G and, after that, plasma is produced.Subsequently, the substrate carrying table is moved to the position F.With this procedure, the amount of local processing of the substrate 2at the plasma production can be suppressed to a very low level of anorder of one-tenth to one-hundredth, for example.

As described above, the plasma producing zone and the substrate to beprocessed are kept away from each other and, after that, plasma isproduced. After the plasma discharging is stabilized, the plasmaproducing zone and the substrate are approximated to each other. Withthis procedure, only ions of locally produced plasma are prevented frombeing incident on the substrate, such that a uniform ion density can beprovided over the whole surface of the substrate.

EXAMPLE 1

An example of plasma processing that uses the plasma processingapparatus shown in FIG. 1 will be explained below.

Cooling water flows through the cooling water flowpassage 10, to coolthe endless circular waveguide tube 8 to a room temperature. While theinside pressure of the plasma processing chamber 1 is monitored by usingthe pressure detector 24, the vacuum pump 26 is operated and, by usingthe pressure adjusting valve 25, the inside pressure is adjusted to 0.1Pa or lower. The substrate carrying table 3 is heated by the heater 4 to200° C. A substrate 2 having a silicon oxide film of 2 nm formed on itssurface is then conveyed to the substrate carrying table 3, and it isplaced thereon. Subsequently, a nitrogen gas is introduced into theplasma processing chamber 1 through the processing gas introducing means5, at a flow rate of 200 sccm. Then, by adjusting the pressure adjustingvalve, the inside of the plasma processing chamber is held at 133 Pa.Microwaves of 1.5 kW is supplied from a microwave voltage source intothe plasma processing chamber 1 through the endless circular waveguidetube 8 and the dielectric material 7, whereby plasma is produced insidethe plasma processing chamber 1. The microwaves introduced into theendless circular waveguide tube 8 are bisected left and right, and theyare introduced into the plasma processing chamber 1 from the slots 11and through the dielectric material 7, whereby plasma is generated. Thisplasma is produced locally and then it is spread over the whole surfaceof the dielectric material window 7. Due to the presence of pressure 133Pa, however, it is reduced rapidly as the distance from the dielectricmaterial window 7 increases. At the surface of the substrate 2 which isat a distance 10 cm, the plasma becomes very weak almost as can bedisregarded.

Subsequently, after elapse of 5 seconds, by using the pressure adjustingvalve 25, the inside pressure of the plasma processing chamber ischanged to 13 Pa. Furthermore, after elapse of 10 seconds, the microwavevoltage source is interrupted, the supply of nitrogen gas is stopped,and the plasma processing chamber 1 is vacuum evacuated to a level of0.1 Pa or lower. After this, the substrate 2 is conveyed out of theplasma processing chamber 1.

The nitrogen density distribution of the thus processed substrate wasmeasured by using an optical film thickness gauge, and it was foundthat, as compared with a case where a substrate was processed only at 13Pa, the uniformness was improved by about 20%.

As shown in the example of FIG. 2, at a pressure 130 Pa the nitrogenions of the plasma decrease rapidly with an increase of the distancefrom the plasma producing zone. Also, at 13 Pa, they reduce gradually.Where the distance between the dielectric material window 7 and thesubstrate 2 to be processed is 10 cm, the ion density at 133 Pa is 5% ofthat at 13 Pa.

Hence, the inside gas pressure of the reaction container is first raisedto about 130 Pa and then plasma is produced and, after that, the gaspressure is lowered to below 130 Pa. With this procedure, only ions oflocally produced plasma are prevented from being incident on thesubstrate to be processed, such that a uniform nitrogen density can beprovided over the whole surface of the substrate.

Although the embodiments and the example described above all concern acase wherein nitrogen is injected into a silicon oxide film, the presentinvention is not limited to use of nitrogen, but it is effectivelyapplicable to use of hydrogen, oxygen, B, P, As and halogen, forexample. Furthermore, the applicability of the present invention is notlimited to a substrate having a silicon oxide film formed on itssurface. The present invention is effectively applicable to injection toa substrate consisting of Si, Al, Ti, Zn, Ta, Bi, Sr, C, Zr, Ba, Yb, Pb,Mg, K, or Nb, for example, a substrate consisting of a compoundincluding any one of these materials, or a substrate with an oxide film,a nitride film or a compound film of any one of these materials.

While the invention has been described with reference to the structuresdisclosed herein, it is not confined to the details set forth and thisapplication is intended to cover such modifications or changes as maycome within the purposes of the improvements or the scope of thefollowing claims.

This application claims priority from Japanese Patent Application No.2004-220210 filed Jul. 28, 2004, for which is hereby incorporated byreference.

1. In an apparatus for processing a substrate to be processed, in areaction container by plasma, the improvements comprising: interceptingmeans for substantially intercepting incidence of ions of the plasmaupon the substrate, for a predetermined time period from start ofproduction of the plasma.
 2. An apparatus according to claim 1, whereinsaid intercepting means includes pressure controlling means forincreasing a gas pressure inside said reaction container, forsubstantial interception of ions.
 3. An apparatus according to claim 1,wherein said intercepting means includes a shutter disposed between aplasma producing zone and the substrate, for substantial interception ofions.
 4. An apparatus according to claim 1, wherein said interceptingmeans includes a stage for retracting the substrate to a position not tobe irradiated with ions, for substantial interception of ions.
 5. Anapparatus according to claim 1, wherein said intercepting means includesa stage for moving the substrate away from a plasma producing zone, forsubstantial interception of ions.
 6. An apparatus according to any oneof claims 1-5, wherein the plasma is microwave plasma.
 7. In a method ofprocessing a substrate to be processed, in a reaction container byplasma, the improvements comprising: substantially interceptingincidence of ions of the plasma upon the substrate, for a predeterminedtime period from start of production of the plasma.